Electrical terminal structures



Sept. 29, 1959 H. w. CAIN ETAL ELECTRICAL TERMINAL STRUCTURES Filed Aug. 20, 1957 rin s Y s RWY w OAL. R m E 7 W H A 1 5 V 6 H I H 3 y 0 z, m N T A Z 0 [0 L m I 7 u 5 li i: a 6 i I 3 Z u 2 3 United States Patent 2,906,990 ELECTRICAL TERMINAL STRUCTURES Harry W. Cain, Greenwi Conn., and John J. Shively,

' New York, N.Y.

Application August 20, 1957, Serial No. 679,175

4 Claims. (or. 339-205 tween stations, and the end portions contain the usual screw holes 14 for attachment of the block to a supporting surface.

Referring to Figure 2, an elongated contact and conducting plate 15, preferably of brass or bronze, is disposed flat on the block at the bottom of typical station 11, the sides of the station cavity being shaped to conform snugly to the edges of the plate. Small downwardly turned lips 16 on the outer ends of the plate extend into cavities 17 in the block 10. The plate 15 has a central screw hole 18, two rectangular slots 19 spaced outwardly therefrom, and two farther outwardly spaced holes .20, the latter being adapted to receive with substantial clearance small bosses 21 on otherwise flat conductor terminals 22 as shown.

Two movable contact members 23, angularly shaped as shown in-Figs. 2 and 3, have downwardly extending curved tongues 24 adapted to fit in the slots 19 in hinge relationship, the block 10 being recessed to provide clearance for the ends of the tongues When in place,

. Fig. 2, the inner faces 25 of the members 23 slope outwardly. A relatively thin spring member 26 is so shaped Another object is to provide a junction structure of p the above nature including a single stationary contact member and two movable contact member s operable by said screw to clamp said conductor terminals between said movable and said stationary contact members.

Another object is to provide means to apply the preswedging relation, whereby the efiective clamping pressure is substantially increased and whereby any tendency toward loosening of the screw under vibration is eliminated.

A further object is to provide a structure of the above type in which the conductor terminals may readily be snapped into place in the junction without removal of the screw.

A still further object is to provide a structure of the above type wherein tightening of the screw produces a final wiping action between the contact members and the conductor terminals, whereby the electrical conductivity between the contact surfaces of the junction is maximized.

Other objects and advantages of the invention will appear. during the course ofthe, following descriptionin connection with the accompanying drawings, in which Figure -l is a fragmental plan view of a terminal block' embodying a preferred form of the invention;

Figure 2 is a cross-sectional elevational view of the block of Figure 1 as seen on the lines 2-2, Fig. 1;

Figure 3 is an exploded perspective view illustratingthe disassembled relationship of the stationary contact member and one of the movable contact members, Figs.

land2; v

Fig. 4 is a cross-sectional view similar to Figure 2 but illustrating an alternativeembodiment of the device; Figure 5 is a perspective detail view 'of the type of movable contact member used in the embodiment shown in Fig. 4; and U r Figure 6 is a fragmental detail illustration of the manner in which two conductor terminals are clamped between a single movable contact member and the stationary contact member, Fig. 2. I

Referring to Figure l, the numeral 10 designates a terminal block body of insulating material. The body may be provided with any desired number of junction stations, dependent on therequirement of the circuit or circuits to which the device is to be'applied, but as the structure'is the same in all stations, onlyone end-of the block containing stations 11 and 12 is shown for purpose of illustration. Insulating barriers 13 are provided bethat whenit is in the clamped position its sides rest flat against the inner sloping faces of the 'contact'members 23, while the outward extensions 27 overlie the upper angle bends 28 of the contact'members.

However, the spring 26 is initially formed so that when unassembled or released its sides assumea substantially greater outward angle thanwhen clamp as shown; 1

A central screw 29 is threaded into a metallic insert 7 30 embedded in the insulating body 10. Under the head sure of 'the screw to the movable contact members in slotted sufiiciently to provide for slight lateral movementand rocking under certain conditions hereinafter explained.

Operation When it is desired to install terminals 22 in the device, the screw 29 is not removed but is backed up or loosened sufiiciently to allow the spring 26 toflex outward'andat the same time raise the wedge 32. Under these conditions the outward pressure of the spring holds the mem-' bers 23 rocked outwardly so that the lower bends of their upturned toes 34 are pressed resiliently against, the-stationary contact member15 prior to the insertion of the terminals. V.

To insert the terminals 22, the latter are simply pushed inward, rocking the members-23 against the resilient force of the spring 26, until the bosses 2'1 snap into the holes 20 in the stationary contact member 15. Thereupon the screw 29 is tightened, forcing the wedge 32 downwardly. The multiplied lateral pressure due to the wedge angle, acting directly through the flat of the spring 26 on the contact members 23, forces the toes 34 power-- fully against the terminals 26, securely locking the latter againstany possible accidental loosening or withdrawal. The wedge 32 and the movable contact members, while of relatively thick construction to withstand theheavy clamping pressures, are made of resilient material such. Therefore, in the tightening process a slight flexing occurs in these parts. This flexing as spring steel or bronze.

of the-members 23 causes the toes 34 to exert an outward to augment surface transmission and to prevent corrosion.

Patented Sept. 29, 1959,

While the mechanical advantage of the wedge 32 permits heavy clamping pressures to bedeveloped without undue strain on the screw 29, the slight resiliently flexed conditi on of the parts when in fully clamped position acts together with the lock washer 31 to prevent any possibility of loosening under vibration. It will be noted that as the movable contact members. 23, the spring 26 and wedge 32 are all of conducting material, their clamped assembly provides a second electrical path between opposite terminals 22, augmenting the direct path through the stationary contact and conducting member 15.

Figure 6 illustrates the manner in which two terminals 22 may be inserted in a single side of a junction station. In this case the boss 21 of the lower terminal 22 snaps into the hole 20 as previously explained, while the boss 21 of the upper terminal similarly snaps behind the curved lower surface formed by the up-turned toe 34 of the movable contact member 23. It will be noted that the outer inclined or curved surfaces of the toes 34 and the lips 16 of the stationary contact member 15v act as guides for easy insertion of the terminals, while side guidance for the terminals is provided in the insulating block asv shown in Figure 1.

The final clamping action of the device when employing two terminals on a single side is the same as that previously set forth for single terminals. In case two terminals are installed in one side and either one or no terminal in the other, the slotted hole 33 and spring lock washer 31, Fig. 2, allow the slight lateral and rocking motion of the wedge 32 necessary for the latter to adjust itself effectively to the differing inclines of the movable contact members 23.

From the foregoing description and by examination of Fig. 2, it will be evident that all the contact and clamping parts of the device are assembled from the top of the solid insulating block 10, being held therein by the screw 29. In addition to the obvious advantage of easy initial assembly, this structure presents a very great advantage over blocks in which essential parts are either permanently embedded or assembled from the bottom. Take for illustration a ten station block injured at one station, for example by inadvertent insertion of a live terminal which has caused arcing and consequent burning of the contact surfaces. In the'case of permanently embedded contact parts, the remedy would probably entail discarding the entire block, while in the case of bottom-assembled parts the block would at leasthave to be removed from its support; either case would require disturbance of all the other circuits served by the tenstation unit.

On the other hand, in case of similar injury to the structure at a station of the present invention, simple removal of the screw 29 at that particular station permits easy removal of all injured parts and installation of replacements, without any disturbance of the other circuits and without removal of the block from its support.

The embodiment of the invention shown in Fig. 4 is of the same general construction as that of Fig. 2, except that it is adapted to receive the conductor terminals 22 vertically instead of horizontally with respect to the plane of the supporting surface. For this purpose the stationary contact member 35, made of relatively thick material for rigidity, is U-shaped with substantially 'vertical sides 36 fitting within buttresses 37 formed on the insulating block 38. The movable contact mem bers 39, instead of the angular form shown in Fig. 2, are shaped .as shown in perspective in Fig. 5, each comprising a flat central wedging portion 40, an upper outwardly formed contact toe 41, and a lower inverted T- shaped hinge tongue 42. The stationary contact member 35, Fig. 4, has a'central longitudinal slot 43 of slightly greater width than the shank of the tongue 42. Prior to assembly of the contact member 35 in the block 38 the tongues of the members 39 are inserted flatwise in the slot 43 and the movable members are then turned crosswise so that when assembly is complete as shown in Fig. 4, the wings 44 of the tongues underlie the member 35 beyond the edges of the slot, thus preventing upward withdrawal of the members 39. The spring member 45, which furnishes resilient pressure to the members 39 during insertion or withdrawal of conductor terminals, conforms closely to the lower contour of the wedge 32 when clamped asv shown.

The operation and advantages of the embodiment shown in Fig. 4 are substantially the same as those explained with respect to Figure 2, the only practical difference lying in, the vertical instead of horizontal reception of the terminals. It will be evident that if desired for particular purposes the same general structural combination may readily be adapted to various terminal angles other than horizontal or vertical. Also it will be evident that if desired the horizontal embodiment of Fig. 2 may be provided with the same type of T and slot hinging arrangement as that employed in Figures 4 and 5. Thus while the invention has been set forth in preferred form, it is not limited to the precise structures illustrated, as various modifications may be made without departing from the scope of the appended claims.

We claim:

1. In an electrical junction device, in combination, an insulating block having therein a station recess, a stationary contact and conducting member in said recess and having contact surfaces at opposite ends thereof adapted to be engaged by electrical conductor terminal members, a pair of movable contact members hinged to said stationary contact member, said movable contact members having opposed outwardly sloping inner surfaces and outer contact toes adapted to engage the conductotr terminal members, means forming a threaded socket in said block, a unitary wedge between said outwardly sloping surfaces of said movable contact members, and a screw disposed through said wedge to engage said socket and adapted when tightened to force said wedge inwardly to apply wedging pressure to said sloping surfaces, whereby said contact toes may be pressed firmly against the conductor terminal members to clamp the same directly between said movable contact members and said stationary contact member.

2. The combination claimed in claim 1 including resilient means engaging said movable contact members to urge said contact toes toward said stationary contact surfaces when said wedging pressure is released.

3. The combination claimed in claim 1 wherein said movable contact members are made of resilient material and proportioned to flex under said wedging pressure, whereby said contact toes may apply a Wiping movement between said contactsurfaces as said pressure is increased.

4. The combinetion according to claim 1 wherein said wedge has therein a central slot through which said screw is disposed, said slot having a long-dimensional centerline which is directed toward said sloping surfaces of said movable contaet members and which lies in a plane perpendicular to both said sloping surfaces to permit rocking self adjustment of said wedge between said sloping surfaces, and including a resilient lock washer disposed between the head of said screw and said wedge.

References Cited in the file of this patent UNITED STATES PATENTS 1,466,735 Williams Sept. 4, 19 23 2,437,339 Webster Mar. 9, 1948 FOREIGN PATENTS 563,909 Great Britain Sept. 5, 1944 731,424 Germany July 14, 1943 

